[Reddit]
Just below the top layer of our skin, the epidermis, the human body reveals a vast collection of hair follicles, sweat glands, muscles and nerve endings – and it is these sensory nerve endings that react to being tickled.
The nerve endings in your skin react to being touched unexpectedly, sending electrical messages to your brain, eventually making it to the somatosensory cortex (which recognises pressure/touch) and the anterior cingulate cortex (which recognises pleasure. The combination of both produces the telltale response in our cerebellum – the part of the brain that regulate movement.
It has to be spontaneous – you literally cannot tickle yourself; researchers have proven then if you try to tickle yourself, you know it’s coming, and your cerebellum prepares your body not to react.
Another way to ward off being tickled is to put your hand on your tickler’s one – a trick used by doctors all over the world. In doing so, your own hand follows the same motion as the tickler, which cons your cerebellum into thinking you’re the one trying to tickle.
But even if you cannot tickle yourself, you should certainly be tickling others – it is regarded as an essential tool of human behaviour.
Along with the peals of laughter tickling triggers, it is also a tool for social bonding, with evolutionary scientist Charles Darwin taking note of its importance. When mothers dote on their darling babies with tickles, the baby’s laughter causes the mother to tickle more, creating communication between the pair.
It’s not all fun and games, though, as tickling’s other major role is protection. In this form, known as knismesis, the body uses the tickling stimulus to draw attention to predators and parasites. It’s how you know when a fly lands on your arm, and why you feel phantom tickles when dealing with spiders.
Protection is also why the body’s most ticklish spots are also often the most vulnerable. The sides of the torso and the soles of the feet, along with ear openings make for the best places on the body to trigger tickling convulsions.
Researchers have also revealed that men prefer being tickled to women. Almost twice as many women as men in a Provine survey said that they found tickling to be “very unpleasant,” with the study concluding this may be due to bad experiences related to non-consensual touching.
But those of us who do enjoy it are not alone in the animal kingdom; both gorillas and rats laugh like humans when they’re tickled, suggesting that the response has been part of evolution dating back 60m years.
